1. Field of the Invention
This invention relates to a tilt switch, more particularly to a tilt switch which is adapted to be mounted on a support and which will establish an electrical connection between central and surrounding electric contact terminals that are mounted on the support when the support is tilted.
2. Description of the Related Art
A conventional tilt switch generally includes an insulating housing with a bottom-opened accommodating space for receiving an electrically conductive ball member. An insulating cover is disposed to cover the opening and has a plurality of through holes such that a plurality of elongate electric contact terminals can be press fitted within the through holes to contact with the ball member when the housing is in an upright direction. Outside ends of the terminals are soldered on an electric contact member of a circuit board. With such a construction, the conventional tilt switch is complicated and is inconvenient to assemble.
The object of the present invention is to provide a tilt switch which is simple in construction and which is easy to assemble.
According to this invention, the tilt switch is adapted to be mounted on and to be in electric contact with a support in an upright direction. The tilt switch includes a central electric contact member which is adapted to be disposed on the support, and which defines a rolling area and a central line that extends in the upright direction and normal to the rolling area. A surrounding seat member is adapted to be disposed on the support, and surrounds the central electric contact member. The seat member has at least one first electric contact terminal which is spaced apart from the central electric contact member. An electrically conductive ball member is rollable on the rolling area. An electrically conductive shell member includes a surrounding lower edge which is disposed on the seat member and which has at least one second electric contact terminal that extends radially and outwardly from the surrounding lower edge and that is in electric contact with the first electric contact terminal, and a surrounding wall which extends from the surrounding lower edge in the upright direction and which surrounds the central line to terminate at a surrounding upper edge. The surrounding wall has an inner peripheral surface which faces towards and which surrounds the central line, and which cooperates with the support to confine an accommodating space for rollably accommodating the ball member. The inner peripheral surface is of such a dimension that a shortest one of distances, each of which is measured between two respective points on the inner peripheral surface opposite to each other relative to the central line, is larger than a diameter of the ball member. The ball member is disposed on the rolling area so that when the rolling area remains in a horizontal plane, the ball member is retained on the rolling area without being in contact with the inner peripheral surface. Once the rolling area is tilted from the horizontal plane, the ball member will move by virtue of gravity to contact with the inner peripheral surface so as to establish an electrical connection between the central electric contact member and the first electric contact terminal. A cap member is disposed on and is formed integrally with the surrounding upper edge to prevent movement of the ball member out of the accommodating space in the upright direction without hindering the rolling of the ball member on the rolling area.